Read PRR Chapter 7

Purpose

• We continue laying the foundations of learning ROS
• We learn how to use sensors and motors to control the robots basic behaviors
• I realize this is difficult and things don’t always just work the way you expect.

Do this

• Please read Chapter 7 and try to really understand how things work.
• Remember to refer to 7: Wander Bot for potentially supplementary information.
• Run some the code in samples and watch it in the simulator

Consider this as you read

1. As we are talking about sensors, think about this: In the Red Light! Green Light! program what plays the role of a sensor?
2. This is tricky: the formula on page 104: bearing = msg.angle_min + i * msg.angle_max / len(msg.ranges) is incorrect (i.e. it’s an error in the book!) What is the correct formula, or what is the error?
3. In Wander-bot, where is the code that assures that the robot doesn’t run into a wall when it is wandering? What line(s).